It was well known to use variable-angle inlet guide vanes (commonly referred to as variable inlet guide vanes, or VIVGs) in gas turbines having radial-to-axial intake. Changing the angle of the guide vanes, and more specifically the orientation of the trailing edge, between the radial and the tangential (i.e. circumferential) orientations changes the characteristics of the intake flow, which can allow adapting the intake flow to varying operating conditions.
Gas turbine engines or generators with variable-angle inlet guide vanes, such some as turboshafts, auxiliary power units (APUs) and small turboprops for instance, were known to be prone to a noise issue commonly referred to as “whistle”. Various approaches were proposed to address occurrences of whistle. While these approaches were satisfactory to a certain extent, there remained room for improvement. In particular, it was found that such former approaches had limited effectiveness in that a) they did not reduce the whistle to a satisfactory level and/or b) they introduced an inconvenient or problematic amount of aerodynamic losses.